"And it’s an opioid that’s associated with novel risks because of the variability in how it’s being formulated, sold and used recreationally and by those who are seeking to self-medicate for pain or who use kratom to treat opioid withdrawal symptoms," FDA Commissioner Scott Gottlieb wrote.

While opioids and kratom have similar effects on the brain, Coley Oh, the owner of Rooted Kava Lounge, said they have different results.

“It has very light effects. I don’t want anyone to be disillusioned that it’s something that they could achieve a high from,” she said.

Oh said the store's distributors provide lab test results for every strain sold at the lounge, and that there is nothing synthetic about kratom.

She added that customers use kratom for pain management, anxiety, or ADHD.

Benjamin Baker has used kratom for years after breaking his back, and said it helped him stop taking three prescribed painkillers.

“I was on a cane. I’m not on that anymore," he said. "It literally saved my life. That’s not hyperbole. It saved my life."

Baker said customers should ultimately be responsible for using kratom if they choose to try it.

"This is something that can be effective for a lot of different people for a lot of different reasons," he said. "It's up to you to decide how to use it and whether you're responsible with it, just like it's up to you to put your brakes on at the stoplight."

Beyond their war of words, the row touched on several sensitive issues in Trump's White House, including a lack of racial diversity, security in the executive mansion and a culture that some there feel borders on paranoia.

Beyond their war of words, the row touched on several sensitive issues in Trump's White House, including a lack of racial diversity, security in the executive mansion and a culture that some there feel borders on paranoia.